Computer technology can help people work more efficiently, exercise control over their environments, and better enjoy their lives. However, the advantages that technology brings to people are sometimes undercut by the complex and unnatural modes of interfacing with the technology. In a technologically equipped home, for example, residents may be overwhelmed by the task of keeping numerous independent systems—e.g., security, home-theatre, and climate control systems—keyed to the prevailing preferences, especially if such preferences vary from one family member to the next, evolve over time, or are subject to exceptions.